1. Field of the Invention
The present invention relates to an electrical connector for electroexplosive ignition devices commonly known as electric initiators or squibs. Such devices may be of the bridge wire type and have particular utility in igniter devices for the actuation of collision protection systems for motor vehicle drivers and passengers.
2. Description of the Prior Art
Collision protection systems for motor vehicles, popularly known as "air bag" systems, involve the use of folded bags that typically are mounted on and fastened to the steering wheel and also to the dashboard of the vehicle and are inflated substantially instantaneously by a gas generator or inflator responsively to the onset of a collision, as sensed by a collision sensor. The sensor activates the igniter device of the gas generator by closing an electrical circuit to the bridge wire of the squib through an insulating plug provided at one end of the igniter device from a source of electrical energizing current. The plug is inserted in one end of a cylindrical steel casing that forms the outer casing for the igniter device. An explosive mixture contained in the casing surrounds the bridge wire of the squib.
Typically, the electrical energizing current to the squib is derived from the electrical system of the motor vehicle and is conducted by input conductors or lead wires, referred to hereinafter as "sensor input conductors," that are connected to the sensor and which pass through the insulating plug of the igniter device to the bridge wire and causes the bridge wire to heat to the point of disintegration. The explosive mixture in proximity to the bridge wire is thus heated and caused to be ignited. Such ignition is effective to initiate the ignition of a gas generating charge which is positioned in surrounding relation to the igniter device, resulting in the generation of a volume of gas sufficient to inflate an associated folded air bag.
A characteristic of electric squibs is that the bridge wire is susceptible of being heated and fired by extraneous radiant energy that tends to be induced in or picked up by the sensor input conductors to the squib from nearby radiation sources. Such radiant energy which may be of electomagnetic or radio frequency origin creates a hazard. Protection against such radiant energy interference is referred to hereinafter, for convenience, as "EMI/RFI protection."
A solution for overcoming this hazard proposed in the prior art involves the use of an assembly of ferrite bodies or beads internally of the squib to absorb or attenuate the extraneous energy which is induced in or picked up by the sensor input conductors to the squib, thereby preventing such energy from reaching the bridge wire, as disclosed, for example, in U.S. Pat. Nos. 3,572,247 to Theodore Warshall and in 4,306,499 to Wayne W. Holmes. In the Warshall patent the sensor input conductors extend from the plug of the squib as "pig tails," as also disclosed in FIG. 2 of the drawings hereof In the Holmes patent, which is assigned to the assignee of the present invention, electrically conducting pins protrude from the squib, to which pins the terminals of an electrical connector are made to mate. Such a "pin type" squib is also shown herein in FIG. 1 of the drawings.
Another solution for overcoming the radiant energy hazard, as embodied in the "Amphenol" connector commercially available from Amphenol Tuchel Elektronix Inc., August Hauser Str. 10, Heilbrohn, Germany, comprises an assembly including a wire coil wrapped around a cylindrical ferrite body that is connected in a series circuit with one of the input conductors or lead wires to one of the connector terminals. Such assembly in the connector for EMI/RFI protection replaces that provided internally of the igniter device in the Warshall and Holmes patents and that shown in FIG. 2 of the drawings hereof, thus simplifying the manufacture of the ingiter device as well as allowing a substantial reduction in the length thereof.
Individual preferences of motor vehicle manufacturers in regard to the type of connector, pig tail or pin type, to be used for connecting the sensor input conductors or lead wires of the squib to the electrical system of the vehicle has introduced undesirable complexity in the manufacture of gas generators. This is because some vehicle manufacturers prefer the pig tail connector while others prefer the pin type connector.
The pin type connector is a female connector that is assembled in cooperative mating relation with the protruding pins of the squib. There are various types of such connectors that are commercially available in addition to the aforementioned Amphenol connector. The Amphenol connector is difficult to permanently attach to the base of the gas generator. It includes an extended portion arranged at a right angle to the terminal portion thereof for enabling the sensor input conductors to run parallel and in close proximity to the base of the gas generator.
The pig tail connector preferred by other vehicle manufacturers, as previously mentioned, has the input conductor assembled inside the squib in cooperative relation with the elements that provide EMI/RFI protection. In this type of connector, as illustrated in FIG. 2 of the drawings, the sensor input conductors or lead wires extend out of the plug at the end of the squib as pig tails. A disadvantage with such a pig tail connector arrangement, from the standpoint of the manufacturer of the collision protection system, is that with the sensor input conductors assembled inside the squib to provide EMI/RFI protection, undesirable extension of the length of the squib results. The extension is sufficient to necessitate substantial modification in the structure of the gas generator, particularly in the structural arrangement of the base thereof, for the elongated squib to be employed therewith, as is readily apparent from a comparison of the gas generator of FIG. 2 hereof with that of FIG. 1.
It is evident, therefore, that in order to satisfy the individual preferences of the vehicle manufacturers in regard to the type of connectors to be used, the manufacturer of the collision protection system has found it necessary to provide two different configurations of squibs, two different configurations of bases for the gas generator, and two different squib assembly processes. This not only introduces undesirable complexity into the manufacture and assembly of the collision protection system but adds substantially to the cost thereof.
Thus, there is a need and a demand for an improved connector for connecting the sensor input conductors to the squib and to a source of electrical current such as the electrical system of a vehicle in order to eliminate the need for such duplication of squibs, gas generator bases, and squib assembly process while providing the necessary EMI/RFI protection and satisfying the individual preferences of the vehicle manufacturers in regard to the type of connector, pig tail or pin type, to be used.